This invention relates to packaging equipment or machines, and more particularly to a web supply arrangement incorporated in a packaging machine.
A packaging machine typically includes at least one web supply arrangement from which a web of packaging material is supplied to the components of the packaging machine from a supply roll. Typically, the edges of the web are gripped, such as by a gripper assembly, that advances the web through the various stations of the packaging machine.
It has been known to provide a desired degree of tension in the web, between the supply roll and the web advancement mechanism, using a dancer roll arrangement. In such an arrangement, the web is trained about one or more dancer rolls in a serpentine path, and the dancer rolls move so as to take up slack in the web and thereby provide a certain degree of tension in the web. While this arrangement functions satisfactorily, it can be undesirable in that the seal surface of the web comes into contact with one or more of the dancer roll surfaces. Since the seal surface of the web is the surface that faces or contacts the package product, this contact of the seal surface with the dancer rolls can be particularly undesirable in a food or pharmaceutical packaging application. While unlikely, it is possible that contaminants may be transferred to the seal surface of the web from the dancer roll surfaces. Furthermore, the dancer roll arrangement requires a certain length of the web material to be exposed to atmosphere before the package is formed. Again, while unlikely, this provides a potential for contaminants to come into contact with the seal surface of the web.
It is therefore an object of the present invention to provide a packaging machine which eliminates the necessity for a dancer roll arrangement to maintain tension in the web prior to engagement of the web with the advancement mechanism of the packaging machine. It is a further object of the invention to provide a packaging machine in which the seal surface of the web does not come into contact with any components of the machine before the web is engaged with the advancement mechanism of the packaging machine. It is a further object of the invention to provide such a packaging machine which reduces the length of the web that is exposed to atmosphere between the supply roll and the web advancement mechanism.
The present invention contemplates a web supply arrangement in which tension is created in the web of packaging material without the use of dancer rolls. Thus, the seal surface of the web material does not come into contact with any component of the packaging machine as the web material is advanced from the web supply roll to a formation station at which cavities are formed in the web material for the subsequent placement of food or other products. In accordance with one embodiment of the present invention, the packaging machine includes a mandrel that supports a roll of web material. The mandrel includes a shaft designed to extend through a hollow core of a roll of web material, which is adapted to rotate around the shaft as web material is advanced from the roll of web material. A bladder is associated with the shaft, and is selectively inflatable to apply pressure against the hollow core to slow rotation of the roll of web material around the shaft. The mandrel may include a shoe slidably coupled to the shaft and configured to engage the hollow core of the roll of web material when the bladder is inflated.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.